In various mobile terminals such as cell-phones, smartphones, and tablet PCs, television receivers, or personal computers, liquid crystal displays (LCDs) have recently been frequently used as flat panel displays (FPDs) utilizing such characteristics as lightweight, thinned form, and low power consumption. In such liquid crystal displays, a liquid crystal layer is provided between a pair of substrates and thin film transistors each employing a low-temperature polysilicon semiconductor layer (LTPS-TFTs) are formed in a matrix as switching elements arranged to drive the liquid crystal layer.
In the case of using such a liquid crystal display for, in particular, a mobile terminal, there has been a need for a technique for intermittently driving the thin film transistors at low frequency when displaying a still image, for example, to reduce the drain on battery power more reliably for lower power consumption. Thus intermittently driving the thin film transistors suffers from a problem of leakage current when the thin film transistors are off. That is, it is necessary to hold the potential of each pixel electrode to maintain the image quality, whereas if the leakage current is large, charges may transfer from the pixel electrode to the signal line, so that the potential of the pixel electrode may vary (the voltage of the pixel electrode may fluctuate) and flickering may appear.